20030189 Ver 1_More Info Received_20041213

FREELAND and KAUFFMAN, INC.
EENGINEERs • LANDSCAPE ARZCHITEcro
Affiliate
Freeland-Kauffman
and Fredeen, Inc.
Bentonville, Arkansas
December 13, 2004
Mr. Danny Smith
N.C. Division of Water Quality
Wetlands Unit
1617 Mail Service Center
Raleigh, NC 27699-1617
Re: 401 Water Quality Certification Revision
DWQ #03-0189-Issued 5/20/03
Additional Information
Lowe's of Forest City, NC
Dear Mr. Smith:
As was requested in DWQ's previous letter, dated October 25, 2004, additional conditions #3 and #4
required that that we provide maintenance agreements and design plans for both the Mebane and
Mocksville. Therefore, please find the above mentioned items enclosed in this package. If you need any
further information or have any questions feel free to contact me at your earliest convenience.
Sincerely,
Craig S. Winnall, P.E.
Attachments: Mebane and Mocksville, NC Maintenance Agreements
Mebane and Mocksville, NC Grading Plans
Mebane and Mocksville, NC Pond Section Details & Profiles Plans
Cc: Mr. Taft Tucker, Lowe's Companies Inc.
[R@a'0'F[R N
DEC 16 2004
209 West Stone Avenue • Greenville, South Carolina 290509, Telephone &64-233-E5497, Fax [phone]
j ?
Permit No.
(to be provided by DWQ)
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
WET DETENTION BASIN SUPPLEMENT
This form may be photocopied for use as an original
DWO Stormwater Management Plan Review:
A complete stormwater management plan submittal includes an application form, a wet detention basin
supplement for each basin, design calculations, and plans and specifications showing all basin and outlet
structure details.
I. PROJECT INFORMATION
Project Name:
`5 0
, K? C,
Contact Person: M"Clo-S Phone Number: 53.E 1 &5E- LI&EY
For projects with multiple basins, specify which basin this worksheet applies to:
elevations
Basin Bottom Elevation °?4-- ft. (floor of the basin)
Permanent Pool Elevation ft. (elevation of the orifice)
Temporary Pool Elevation a545 I ft. (elevation of the discharge structure overflow)
areas
Permanent Pool Surface Area sq. ft. (water surface area at the orifice elevation)
Drainage Area 2Z. ac. (on-site and off-site drainage to the basin)
Impervious Area 14. 1 `7 ac. (on-site and off-site drainage to the basin)
volumes
Permanent Pool Volume 21t:) cu. ft. (combined volume of main basin and forebay)
Temporary Pool Volume 343 cu. ft. (volume detained above the permanent pool)
Forebay Volume cu. ft. (approximately 20% of total volume)
Other parameters
SA/DA1
Diameter of Orifice
Design Rainfall
Design TSS Removal 2
.3.1) in.
I • b in.
5!5 %
(surface area to drainage area ratio from DWQ table)
(2 to S day temporary pool draw-down required)
(minimum 85% required)
?[R/;:?kRUWk!__ L
D
DEC 1 6 2004
DENR - WATER QUALI
?etiands $Wfnwatc. o_ N.
Form SWU-102 Rev 3.99 Page 1 of,4
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
Footnotes:

When using the Division SA/DA tables, the correct SA/DA ratio for permanent pool sizing should be computed based upon the
actual impervious % and permanent pool depth. Linear interpolation should be employed to determine the correct value for non-
standard table entries.
In the 20 coastal counties, the requirement for a vegetative filter may be waived if the wet detention basin is designed to provide
90% TSS removal. The NCDENR BMP manual provides design tables for both 85% TSS removal and 90% TSS removal.
II. REQUIRED ITEMS CHECKLIST
The following checklist outlines design requirements per the Stormwater Best Management Practices Manual
(N.C. Department of Environment, Health and Natural Resources, February 1999) and Administrative Code
Section: 15 A NCAC 2H .1008.
Initial in the space provided to indicate the following design requirements have been met and supporting
documentation is attached. If the applicant has designated an agent in the Stormwater Management Permit
Application Form, the agent may initial below. If a requirement has not been met, attach justification.
Applicants Initials
(X5 C4) a. The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet).
b. The forebay volume is approximately equal to 20% of the basin volume.
(2-,% cz c. The temporary pool controls runoff from the design storm event.
d. The temporary pool draws down in 2 to 5 days.
&)A e. If required, a 30-foot vegetative filter is provided at the outlet (include non-erosive flow
calculations)
f. The basin length to width ratio is greater than 3:1.
g. The basin side slopes above the permanent pool are no steeper than 3:1.
C? h. A submerged and vegetated perimeter shelf with a slope of 6:1 or less (show detail).
C S i. Vegetative cover above the permanent pool elevation is specified.
A trash rack or similar device is provided for both the overflow and orifice.
A? P" k. A recorded drainage easement is provided for each basin including access to nearest right-
/ of-way.
V 1. If the basin is used for sediment and erosion control during construction, clean out of the

basin is specified prior to use as a wet detention basin.
m. A mechanism is specified which will drain the basin for maintenance or an emergency.
M. WET DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT
The wet detention basin system is defined as the wet detention basin, pretreatment including forebays and the
vegetated filter if one is provided.
This system (check one) 0 does (does not incorporate a vegetated filter at the outlet.
This system (check one) 0 does does not incorporate pretreatment other than a forebay.
Form MU-102 Rev 3.99 Page 2 of 4

Maintenance activities shall be performed as follows:
After every significant runoff producing rainfall event and at least monthly:
a. Inspect the wet detention basin system for sediment accumulation, erosion, trash accumulation,
vegetated cover, and general condition.
b. Check and clear the orifice of any obstructions such that drawdown of the temporary pool occurs within
2 to 5 days as designed.
2. Repair eroded areas immediately, re-seed as necessary to maintain good vegetative cover, mow vegetative
cover to maintain a maximum height of six inches, and remove trash as needed.
3. Inspect and repair the collection system (i.e. catch basins, piping, swales, riprap, etc.) quarterly to maintain
proper functioning.
4. Remove accumulated sediment from the wet detention basin system semi-annually or when depth is
reduced to 75% of the original design depth (see diagram below). Removed sediment shall be disposed of
in an appropriate manner and shall be handled in a manner that will not adversely impact water quality (i.e.
stockpiling near a wet detention basin or stream, etc.).
The measuring device used to determine the sediment elevation shall be such that it will give an accurate
depth reading and not readily penetrate into accumulated sediments.
When the permanent pool depth reads 71CMfeet in the main pond, the sediment shall be removed.
When the permanent pool depth reads?l% 79 feet in the forebay, the sediment shall be removed.
BASIN DIAGRAM
ill in the blank)
0 Permanent Pool Elevation T??'• D
Sediment Re oval El.'4 14,% 75 0
-------------- -- Sediment Removal Elevation 7-94-.75
75%
Bottom Ele ation?•V % --------------------------------------------- ------
Bottom Elevation 4-14. 125%
FOREBAY MAINPOND
5. Remove cattails and other indigenous wetland plants when they cover 50% of the basin surface. These
plants shall be encouraged to grow along the vegetated shelf and forebay berm.
6. If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment through
the emergency drain shall be minimized to the maximum extent practical.
Form SWU-102 Rev 3.99
Page 3 of,4

7. All components of the wet detention basin system shall be maintained in good working order. 4..
I acknowledge and agree by my signature below that I am responsible for the performance of the seven
maintenance procedures listed above. I agree to notify DWQ of any problems with the system or prior to any j`
changes to the system or responsible party.
Print name: ?C??j, V . I? ,??? e 5
Title: ?,Le'- e5Icke 4
Address: P.wv ' - cj l 11 ?,? ? \ 2 ???? fm
Note: The legally responsible party should not be a homeowners association unless more than 50% of the lots have been sold and a
resident of the subdivision has been named the president.
if 11
I c c- l??tc e.
a Notary Public for the State of ???
County of \<E 5 , do hereby certify that??t, \ 41 C?-l
personally appeared before me this y day of t? ,1:924 and acknowledge the due
execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal,
SEAL
My commission expires
Form SWU-102 Rev 3.99 Page 4 of 4

0000, Permit No.
(to be provided by DWQ)
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form may be photocopied for use as an original
DWO Stormwater Management Plan Review:
A complete stormwater management plan submittal includes an application form, a wet detention basin
supplement for each basin, design calculations, and plans and specifications showing all basin and outlet
structure details.
1. PROJECT INFORMATION
Lowe's of Mebane
Project Name:
Contact Person: 'PCb? N k-cui5 Phone Number:. ) 5 - gyp
For projects with multiple basins, specify which basin this worksheet applies to:
elevations
Basin Bottom Elevation 620.0 ft.
Permanent Pool Elevation 623.0 ft.
Temporary Pool Elevation 6 2 4.3 5 , ft.
areas
Permanent Pool Surface Area
Drainage Area _
Impervious Area _
volumes
Permanent Pool Volume
Temporary Pool Volume
Forebay Volume
Other parameters
SA/DA1
Diameter of Orifice
Design Rainfall
Design TSS Removal 2
32,950
20.06
16.81
(floor of the basin)
(elevation of the orifice)
(elevation of the discharge structure overflow)
sq. ft. (water surface area at the orifice elevation)
ac. (on-site and off-site drainage to the basin)
ac. (on-site and off-site drainage to the basin)
7 5, 4 4 3 cu. ft. (combined volume of main basin and forebay)
5 8 , 2 5 4 cu. ft. (volume detained above the permanent pool)
19 , 2 31 cu. ft. (approximately 20% of total volume)
3.50
(surface area to drainage area ratio from DWQ table)
(2 to S day temporary pool draw-down required)
(minimum 85% required)
Form SWU-102 Rev 3.99 Page 1 of 4
Footnotes:
1 When using the Division SA/DA tables, the correct SA/DA ratio for permanent pool sizing should be computed based upon the
actual impervious % and permanent pool depth. Linear interpolation should be employed to determine the correct value for non-
standard table entries.
2 In the 20 coastal counties, the requirement for a vegetative filter may be waived if the wet detention basin is designed to provide
90% TSS removal. The NCDENR BMP manual provides design tables for both 85% TSS removal and 90% TSS removal.
H. REQUIRED ITEMS CHECKLIST
IN
The following checklist outlines design requirements per the Stormwater Best Management Practices Manual
(N.C. Department of Environment, Health and Natural Resources, February 1999) and Administrative Code
Section: 15 A NCAC 2H. 1008.
Initial in the space provided to indicate the following design requirements have been met and supporting
documentation is attached. If the applicant has designated an agent in the Stormwater Management Permit
Application Form, the agent may initial below. If a requirement has not been met, attach justification.
Applicants Initials_
..?- a.
?GJ b.
c.
?-? d.
e.
9-
h.
CS ?.
,cJ 1? k.

The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet).
The forebay volume is approximately equal to 20% of the basin volume.
The temporary pool controls runoff from the design storm event.
The temporary pool draws down in 2 to 5 days.
If required, a 30-foot vegetative filter is provided at the outlet (include non-erosive flow
calculations)
The basin length to width ratio is greater than 3:1.
The basin side slopes above the permanent pool are no steeper than 3:1.
A submerged and vegetated perimeter shelf with a slope of 6:1 or less (show detail).
Vegetative cover above the permanent pool elevation is specified.
A trash rack or similar device is provided for both the overflow and orifice.
A recorded drainage easement is provided for each basin including access to nearest right-
of-way.
If the basin is used for sediment and erosion control during construction, clean out of the
basin is specified prior to use as a wet detention basin.
in. A mechanism is specified which will drain the basin for maintenance or an emergency.
III. WET DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT
The wet detention basin system is defined as the wet detention basin, pretreatment including forebays and the
vegetated filter if one is provided.
This system (check one) 0 does does not incorporate a vegetated filter at the outlet.
This system (check one) 0 does ID does not incorporate pretreatment other than a forebay.
Form SWU-102 Rev 3.99 Page 2 of 4

Maintenance activities shall be performed as follows:
1: . After every significant runoff producing rainfall event and at least monthly:
a. Inspect the wet detention basin system for sediment accumulation, erosion, trash accumulation,
vegetated cover, and general condition.
b. Check and clear the orifice of any obstructions such that drawdown of the temporary pool occurs within
2 to 5 days as designed.
2. Repair eroded areas immediately, re-seed as necessary to maintain good vegetative cover, mow vegetative
cover to maintain a maximum height of six inches, and remove trash as needed.
3. Inspect and repair the collection system (i.e. catch basins, piping, swales, riprap, etc.) quarterly to maintain
proper functioning.
4. Remove accumulated sediment from the wet detention basin system semi-annually or when depth is
reduced to 75% of the original design depth (see diagram below). Removed sediment shall be disposed of
in an appropriate manner and shall be handled in a manner that will not adversely impact water quality (i.e.
stockpiling near a wet detention basin or stream, etc.): - - - - - -
The measuring device used to determine the sediment elevation shall be such that it will give an accurate
depth reading and not readily penetrate into accumulated sediments.
When the permanent pool depth reads 6 2 0.9 6 feet in the main pond, the sediment shall be removed.
When the permanent pool depth reads 620. 85 feet in the forebay, the sediment shall be removed.
BASIN DIAGRAM
(fill in the blanks)
0 Permanent Pool Elevation 6 2 3. 0
Sediment Re oval El. 6 2 0.8 5 75 o
-------------- -- Sediment Removal Elevation 6 2 0. 9 6 75%
Bottom Ele ation 6 2 0.0 % --------------------------------------------- ----
Bottom Elevation 6 2 0. 0 125%
FOREBAY
MAINPOND
5. Remove cattails and other indigenous wetland plants when they cover 50% of the basin surface. These
plants shall be encouraged to grow along the vegetated shelf and forebay berm.
6. If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment through
the emergency drain shall be minimized to the maximum extent practical.
Form SWU-102 Rev 3.99 Page 3 of 4
7. All components of the wet detention basin system shall be maintained in good working order.

I acknowledge and agree by my signature below that I am responsible for the performance of the seven
maintenance procedures listed above. I agree to notify DWQ of any problems with the system or prior to any
changes to the system or responsible party.
Print name:
©?
Title: Y i C. C ?re S,\Ae,r4-( ? a?? i see C e ? e? 5 n e
Address: RL;,-3U ;Cct? 6CLS4 , N . 1;c.3?1 KeS?y3r? M
- / -,- Y.-
Date:
Note: The legally responsible party should not be a homeowners association unless more than 50% of the lots have been sold and a
resident of the subdivision has been named the president.
a Notary Public for the State of kw&c ico?i na ,
County of do hereby certify that?C) F-? + 1p :s
personally appeared before me this day of and acknowledge the due
execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal,
" OFFICIAL SEAL "
Notary Public, North Carolina
County of Wilkes
SEAL
My commission expires I 425165
y

Form SWU-102 Rev 3.99 Page 4 of 4
FREELAND and KAUFFMAN, INC.
FNoNEERS - LANDSCAPE ARCHITECTS
September 24, 2004
Affiliate
Freeland-Kauffman
and Fredeen, Inc.
Bentonville, Arkaneas
2 ':ua'r'.c+.s+wi,?<:s w.e+mn• .er.?w.r.,.:.w -„?«rws+aisew-
Mr. Danny Smith
N.C. Division of Water Quality
Wetlands Unit Q 0
1617 Mail Service Center
Raleigh, NC 27699-1617 i $EP 2 $ 2004
Re: 401 Water Quality Certification Revision pENR wP QIITY
DWQ #03-0189-Issued 5/20/03 POINT SOURCE BRANCH
Signed Permit Applications/Wet Detention Sup iimif ent Worksheet
Lowe's of Forest City, NC _..?..N?- ?.._ ._w_.----., -
Dear Mr. Smith:
I have. enclosed the signed Permit Applications and Wet Detention Supplement Worksheets for the Lowe's
stores in Mebane and Mocksville, NC. I apologize for the delay in returning the applications to you;
however, it has taken approximately a month to get the signed documents back from Lowe's. As
indicated in our petition to utilize alternate sites, dated July 15, 2004, we had proposed to utilize these
two stores to satisfy the above referenced DWQ permit certification requirements issued in for the Lowe's
of Forest City, NC project. Based on our request, we understand that DWQ had agreed to allow the use
of these two sites to satisfy the requirements; therefore, please respond with written documentation that
the Certification Requirements for the Forest City project have been satisfied. We appreciate all of your
help with this matter and look forward to hearing from you. If you need any further information or have
any questions feel free to contact me at your earliest convenience.
Sincerely,
Craig S. Winnall,
Attachments:. Two Permit Applications and Wet Detention Supplement Worksheets
Copy of the Petition to Utilize Alternate Sites, dated July 15, 2004.
Cc: Mr. Shea Davis, Venture Properties
209 Weat Stone Avenue • Greenville, South Carolina 29609 • Telephone [phone] • Fax [phone]
FREELAND and- KAUFFMAK INC Freel nd''ffman
Inc.
ENGINEERS • LANDSCAPE ARCHITECTS and Fredeen,
July 15, 2004 Bentonville, Arkansas
Mr. Danny Smith
N.C. Division of Water Quality
Wetlands Unit
1617 Mail Service Center
Raleigh, NC 27699-1617 "
Re' 401 Water Quality. Certification Revision
DWQ #03,-0189-Issued 5/20/03
Petition to Utilize Alternate Sites
Lowe's of Forest City, NC
Dear Mr. Smith:
As you are aware, our previous attempt to retrofit to. the Lowe's of Forest City, NCstormwater
management pond in order to comply with the above referenced certification, was rejected by your
agency. As indicated in, previous correspondence with Mr. Gene Hinkle of our- firm and as discussed
during our telephone"conversation on,July 12, 2004, you. indicated. an•option to satisfy the 401: Water
Quality Certification would be to provide water quality BMP's at alternate Lowe's sites within North
Carolina where currently. no water quality requirements exist. Therefore', with-this letter, I am officially
petitioning you to allow the BMP's we have designed for two other Lowe's sites, the first being in
Mebane, NC and the second being in Mocksville,'NC.to be used to satisfy.the Lowe's of Forest City, N.C.
Certification Requirements. The following text its intended to outline the pertinent project information, the
:receiving stream classification, and the water qualityBMP'sthat.peovided for each site..,
The Mebane.site is currently, under, construction and is located on NC Highway 1;19 in Alamance County,
North Carolina (Lat: N 36°04'05", Long: W 79° 1817"). The site is approximately. 16.04 acres with a
total drainage area of 20.06 acres. The site consists entirely of .a new Lowe's Home Improvement Facility
with associated paved driveways and parking" lots.. Lowe's is.also building` and dedicating -a new roadway-.
to the City of Mebane. The runoff from a majority.ofithis roadway will be treated and detained by the on
site stormwater management facility Although not required, a wet detention basin has been designed and
is-being constructed for this facility. ;
The outflow from the pond will drain into the NCDOT1-40/85 nght-of-way`(ROW) at Latitude: N
36°04.'05.84", Longitude: W 7991817.27", which 'makes up the northern property boundary'of the site,
and then into an unnamed tributary of Back Creek. This unnamed tributary drains to the southwest
towards Back Creek. Back Creek is located approximately 4:25 miles from where the runoff exits our site. .
Back Creek eventually drains in the Haw River, approximately %.of a mile downstream from this location. `
According to the United States Environmental-Protection Agencies Web Page, Back Creek and. the
unnamed tributary are not listed as 303D impaired waterways for sediment/siltation. Back Creek is
classified as Class C, NSW. stream. Based on the information contained on the USEPA's website there
were no total maximum daily loads .(TMDL's) reported to the EPA by-the state. A color copy of the area.,
209 West Stone Avenue e Greenville, 5outh Carolina 29609, Telephone [phone] • Fax [phone]

c
Petition to Utilize Alternate Sites
401 Water Quality Certification Revsion (DWQ #03-0189)
Page 2 of 4
around the site is.included as an Attachment that shows the receiving stream is not a 303D Listed
Waterway (shown as red if listed):
In accordance with The North Carolina Department of Environment and Natural Resources Stormwater
Best Management Practices a wet detention pond, will be utilized for this site. The wet detention pond will
be used for water quality control as well as storing the additional runoff created from development of this
site. The runoff will then be released from the pond at pre-developed rates. The pond will require a
Permanent Water Quality Pool, a Temporary Water Quality Pool, and a. staged outlet riser. We determined
the surface area required for,the permanent pool based on the permanent pool depth of 3 feet. The
required surface area is a function of the ratio of the impervious area to the total drainage area based
upon an 85% TSS removal in the Piedmont at a depth of 3 feet. In addition a forebay, equal to about.20%
of the total basin volume was created to encourage early settling. The chart below outlines the wet pond
surface area requirements for the Mebane site:
Lowe's of Mebane Permanent Water Quality Surface Area ,
Total Drainage Area 20.06 acres
impervious Area. 16.81 acres
Permanent Pool Top Elevation - 623.00 feet
Permanent Pool Bottom Elevation 620.00 feet
Permanent Pool Depth 3 feet
% Impervious (I) 83.8%.
SA/DA ratio (From table 1:1) 3.50%
Required Surface,Area 30,583 SF at Permanent Pool
Provided Surface Area 32,950 SF at Permanent Pool
In-,addition a temporary, water quality pool was provided for the volume of runoff generated from the first
1" of rainfall as calculated in accordance with NCDENR's Stormwater Best Management Practices. Manual.
The volume will be based on a drainage area of 20.06 acres and a ,percent impervious of 83.8%: The
following chart outlines the volume-of runoff generated during the 1-inch rainfall event, the orifice size,
and the release time:
Volume to Be Controlled For the. Firs t 11" . of Rainfall.
Required Volume '58,254 cubic feet -
Elevation . 624.35
Diameter of I". Rainfall Orifice 3 inches
Allowable Release over 2 days/ 5 days 0.13 cfsl 0.34 cfs.
Actual Release 0.27 cfs
Actual release time based on common size orifice 2.59 days
Petition to Utilize Alternate Sites
401 Water Quality Certification Revsion (DWQ #03-0189),
Page 3 of 4
The Mocksville site is currently in design and is. located on Yadkinville Road (US 601) at Koontz Road in
Davie County, North Carolina (Lat: N 35°55'075", Long: W 80035'06")., The site is approximately 18.30 •
acres with a total drainage area of 16.28 acres going to our pond. The site consists entirely of a new
Lowe's Home Improvement Facility with associated paved driveways and parking lots. Lowe's will also be
constructing an access drive.for outparcels along US 601; however, will not be developing any of the
outparcels: Although not required, a wet detention basin has been designed and is being constructed for
this facility.
The outflow from the pond will drain into an unnamed perennial stream, which is located along the,
northwest corner of the site. This unnamed perennial stream drains for approximately 1.55 miles to the
south' before`draining into Bear Creek. Bear. Creek eventually drains in the South Yadkin River (at least 8
miles) at the county line between Davie and Rowan Counties. According to the United States
Environmental Protection Agencies Web Page, Bear Creek and the unnamed tributary are not listed as
303D impaired waterways for sediment/siltation. Bear Creek is classified as a.Class C stream. Based on
the information contained on the USEPA's website there were no total maximum` daily loads (TMDL's)
reported. to the EPA by the state. A color copy of the area around the site is included as an Attachment
that shows the receiving stream is not a 303D Listed Waterway (shown as-red if listed):
As previously mentioned above the wet detention pond for this site is being designed in accordancewith
The North Carolina Department of Environment and Natural Resources Stormwater Best Management';
Practices.: We determined the surface area required for 85% TSS removal in the Piedmont with'the
permanent pool depth of 3 feet. The chart below outlines the wet pond surface area, requirements for the
Mocksville site:
Lowe's of Mocksville Permanent Water Quality Surface Area ;
Total Drainage Area 16.28 acres
Impervious Area 12.15. acres
Permanent Pool Top Elevation 797.00 feet,
Permanent Pool Bottom. Elevation' 794.00 feet.
Permanent. Pool Depth 3 feet
% Impervious (I) 74:7%
SA/DA ratio (From Table 1.1) 3.11%
kequired.Surface Area.' 22,054 SF at Permanent PooL
Provided Surface.Area 32,271 SF at Permanent Pool'
i'.
Petition to Utilize Alternate Sites
401 Water Quality Certification Revsion (DWQ #03-0189)
Page.4 of 4
The temporary water quality pool was designed for the volume of runoff generated from the first 1" of
rainfall as calculated in accordance with NCDENR's Stormwater Best Management Practices Manual The
following chart outlines the volume of runoff generated-during the 1-inch rainfall event, the orifice size,
and the release'time based on the site. being 74.7% impervious:
Volume to Be Controlled For the Firs t 1" of Rainfall
Required Volume 42,685 cubic feet .
Elevation 797.98 -
Diameter of 1" Rainfall Orifice 3 inches
Allowable Release over t days/ 5 days 0.25 cfs/ 0.10 cfs
Actual Release 0.22 cfs
Actual release time based on`common-size orifice 2.28 days